During its annual developer conference, the Cupertino, California-based company said the two app platforms will merge next year, allowing apps built for its iOS mobile operating system to also run on Mac computers. Bloomberg reported the planned change in December, but Apple hasn’t talked about it publicly until Monday, when it gave a preview.

The point of this is not to create a single unified OS, Federighi said. But the fact that Apple spoke openly about an initiative that could arrive as late as a year from now is a clear nod to how the tech giant perceives the future of apps.

At WWDC on Monday, Apple said some of its homegrown iOS apps, including Home, Stocks, News, and Voice Memos, would be available later this year on macOS Mojave, the next version of macOS. On the surface, it seems obvious that Apple might make some of its own apps available across different platforms. But behind the scenes, Apple has been building tools third-party developers can eventually use to port their own apps from iOS to MacOS with what Federighi insists will be minimal effort. Apple began this initiative around two years ago, and its own internal software engineers have been beta testing the tools. These four iOS apps for Mac are the products of that testing.

Right now, it seems all-or-nothing; I would have expected apps with both AppKit & UIKit code, interleaved views, etc — but no way if they have separate window servers like now. That may change over timeSteve Troughton-Smith added,

The current approach isn’t really evolvable into hybrid AppKit/UIKit apps at all so I’m not sure where this goes. The way the stack is oriented it’s not even remotely positioned to replace AppKit in the stack. Good for us AppKit lovers I suppose but generally confusing.

It feels like Federighi’s cutting it awfully close on the “unique ergonomics” front, though. Apple itself sells a keyboard for the iPad Pro, and even allows users to move their fingers like they’re using a trackpad when editing text. The iPhone and iMac Pro are about as far as two devices can get from one another, but the MacBook and the iPad Pro are not.

In his interview with Wired, Federighi also pooh-poohed the idea that Apple might make a MacBook with a touchscreen. And yet one of Apple’s greatest arguments against touch on macOS—that Mac software was designed with keyboard and pointing device in mind—is going to very rapidly become obsolete as iOS-sourced apps appear on the Mac in 2019 and 2020.

Although I want to believe Marzipan will kill Electron, I doubt it will. Electron isn’t used by iOS developers who don’t know how to make a Mac app. It’s used by web developers who don’t know how to make a Mac app.

Developer/user question: what features or UI elements does a Mac app need to have to be considered a good platform citizen? i.e. in your opinion what specific things does UIKit/Marzipan need to grow to actually be viable for Mac apps?

In the end, Apple’s UIKit port to macOS raises questions we can’t answer. iOS apps such as News, Stocks, and Home ported to macOS are nice, but, again, I don’t see a stampede of iOS apps crossing the bridge to macOS, not enough to move the Mac volume needle. This leaves us with two possibilities. Either the UIKit move is a titillating but unimportant sideshow, or it’s part of a larger hardware plan for the Mac.

In other words, Frankensoftware might seem like the wretched experiment of a bunch of FOMO-driven executives when you’re struggling to swipe, tap, or shout your way through an interaction with a new product. But from now on, most every connected thing you buy is going to have a little bit of something else in it. And once the companies making those things figure out a way to make these interactions effortless, it won’t seem like such a bad thing.

That’s something that makes me skeptical about the Marzipan dream. Developers who give a crap are already able to make this kind of thing work, and developers who don’t give a crap aren’t going to do it no matter how easy you make it.

Marzipan (candy frosting) is a legacy porting technology: Existing iOS apps can cost more to port to AppKit than they’re worth, but may be worth something as a cheap Marzipan port. Nobody ports their iOS apps to tvOS or watchOS because it’s not profitable, and everyone (in the first world with money) has an iPhone already.

It kind of pisses me off. Because these system apps are also supposed to show developers and users how good these kinds of apps can be. If Apple’s own engineers can’t hit this pitch, it’s a missed opportunity at best and a bad sign at worst.

They’re good enough to launch with, but they’re clearly not the final destination. Initially they’re going to be like every other platform Apple has done. The “defaults” will get developers 90% of the way, and the last 10% is what will make certain apps shine.